TUNNELING-LIKE MAGNETORESISTANCE IN BICRYSTAL LA0.8SR0.2 MNO3-DELTA THIN-FILMS

Epitaxial ferromagnetic La0.8Sr0.2MnO3-delta films have been sputtered on SrTiO3 bicrystal substrates. Etched patterns crossing the bicrysta l grain boundary are compared with identical patterns not crossing it. The films were annealed at different conditions and their magnetoresi stance measured as a function of temperature T and of in plane magneti c field H strength and direction. Annealing at 900 degrees C was found to modify the grain boundary and to increase its magnetoresistance. F or H = +/-80 Oe parallel to the grain boundary and T = 32 K narrow mag netoresistance peaks of 60% height are measured. They are interpreted in the frame of an in plane magnetotunneling structure. (C) 1998 Ameri can Institute of Physics. [S0003-6951(98)04443-X].